The Rockefeller University - Laboratory of Sensory Neuroscience

Hair Cells of the Inner Ear

Screening for Zebrafish Mutations Affecting
Hearing and Balance

Mutation of the Zebrafish's choroideremia Gene
Causes Hair-Cell Degeneration

Paravalbumin 3, A Potent Ca²⁺ Buffer in Hair Cells

Spontaneous Oscillation by Hair Bundles

Electrical Stimulation of Hair-Bundle Movement

Electron-Microscopic Tomographic Analysis of
the Transduction Element

Radixin in the hair bundle

Dynamical instability and the ear's active process

Sunday, July 20, 2008

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Electron-Microscopic Tomographic Analysis of the Transduction Element

The transduction element of a hair cell comprises the tip link connecting adjacent stereocilia, the associated mechanosensory channels, and the myosin-based molecular motor that adjusts the channels' open probability during the process of adaptation. We are analyzing the structure of the transduction element by electron-microscopic tomography, a procedure in which up to 150 micrographs are acquired as a 120-nm-thick section is tilted through successive angles of 1�. After subcellular structures have been reconstructed in three dimensions from the resulting stack of data with a resolution of about 5 nm, the images may be computer-filtered to reduce noise. Tomographic images delineate the multi-stranded nature of the tip link and reveal connections between the actin cytoskeleton and the insertional plaque, the electron-dense structure at the tip link's upper insertion. Because our group's earlier work has suggested that adaptation to sustained stimuli involves the activity of actin-based molecular motors at this site, these connections may include myosin molecules. We are now identifying molecular components of the transduction element by model fitting and immuno-electron microscopy.